Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> pint;
#define rep(i, n) for(ll i = 0; i < (n); i++)
int main() {
  ll H,W,cnt=0,dx[4]={-1,1,0,0},dy[4]={0,0,-1,1};
  cin>>H>>W;
  vector<string> v(H);
  rep(i,H) cin>>v[i];
  vector<vector<ll>> w(H,vector<ll>(W,-1));
  rep(i,H) rep(j,W) if(v[i][j]=='#') w[i][j]=-2,cnt++;
  queue<pint> que;
  que.push(pint(0,0));
  w[0][0]=0;
  while(!que.empty()){
    auto c=que.front();que.pop();
    rep(i,4){
      ll ny=c.first+dy[i];
      ll nx=c.second+dx[i];
      if(nx<0 || ny<0 || W<=nx || H<=ny) continue;
      if(w[ny][nx]==-1){
        w[ny][nx]=w[c.first][c.second]+1;
        que.push(pint(ny,nx));
      }
    }
  }
  if(w[H-1][W-1]==-1) cout<<-1<<endl;
  else cout<<W*H-cnt-(w[H-1][W-1]+1)<<endl;
}